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Forum: Post Your Photos!
07-02-2013, 02:12 AM
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Those ants live in frosty conditions?
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Forum: Post Your Photos!
07-02-2013, 01:46 AM
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congratulations for that awesome shot - what is the ground it is standing on? ;)
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Forum: Post Your Photos!
07-02-2013, 01:39 AM
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Forum: Pentax K-5 & K-5 II
02-20-2013, 02:51 AM
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My k5-I shows the same freezing behavior ocasionally over multiple firmware versions and multiple lenses dfa 100 WR da*16-50.
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Forum: Pentax K-5 & K-5 II
11-22-2012, 05:19 PM
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Thanks for the input. Next question is why does it appear on my K5 and on another with identical settings not? I am not sure whether this exif tag is related to my AF problems (my camera also freezed a couple of times), but is definitive an anomaly and I could not sell my K5 with good conscious when I decide to upgrade at some point, so I contacted the vendor..
195000 sounds like a pretty low number to me given the number of images in googles database.
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Forum: Pentax K-5 & K-5 II
11-22-2012, 03:55 PM
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true.
However please stop discussing this particular photo from the first week of me using the camera. I just opened my folder and dragged the first photo not displaying a human or violating any personal rights because this thread is about the exif.
I did not find any underlying pattern. It seems to be random though pronounced in lower lightning conditions (I am quite sure it is not the systematic tungsten error though since the camera produces perfectly focused shots on a regular basis).
As I sad I assumed to be the reason myself until the day I used the K5 of a fellow photographer and achieved significantly higher accuracies. Then I stumbled upon this weird exif entry, which I happened to find in every single shot I made with the camera over the last ~13 months:
focus mode: unknown (272)
also does your k5 also produce a focus mode 2: af-s
tag?
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Forum: Pentax K-5 & K-5 II
11-22-2012, 01:21 PM
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Ahh this particular shot is more about showing the exifs, than about the AF problem. I guess anyone that is able to contribute to this topic also knows about the look of blurred pictures ;)
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Forum: Pentax K-5 & K-5 II
11-22-2012, 12:14 PM
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My K5 (manufacture date May 2011) seems to suffer from random autofocus problems. The problem is present since purchase ( I always thought it's me) and persisted through all firmware updates and data resets. The problem occured using four different lenses, the exifs show "Unknown (272)" in the focus mode tag. Has anyone more information about this error? I did not find anything so far..
See exifs of the attached image for details.
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Forum: Pentax DSLR Discussion
10-28-2012, 07:26 AM
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Forum: Pentax DSLR Discussion
10-18-2012, 03:03 AM
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Heya, thanks for the input. Of course these findings are only valid for the pentax K-5 but ofc it maybe possible that they also apply to other camera models.
I provided my settings so others can retrace and maybe even replicate those results. Usually I work in science, maybe it's just one of those odd profession habbits. The parameters listed might critically affect the functioning of exposure correction.
"actually the shutter speed is something close to the hand held rule of thumb for the sensors, i.e. 1/(FL*1.5) . In fact the process is actually that it will retain the shutter speed at 1/(flx1.5) until the ISO can be reduced to ISO minimum at which point it raises shutter speed, the camera always adjusts ISO before other settings"
That's what I suspected first, too. But how would you explain the 1/50s @ 50mm then? According to that algorhithm it should be 1/75s.
Do you have any evidence for this maximizing MTF behavior of the pentax K5?
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Forum: Pentax DSLR Discussion
10-16-2012, 08:10 AM
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Dear Forum,
first a few words about me because it is my first post on this platform. My name is Florian, I am 24 study Neuro Cognitive Psychology in Munich. I focus mainly on Nature Photography. I profited from this community for quite a while now so I feel like it's time to give something back.
After a long and stupid discussion on a German platform about how the exposure correction setting changes actual exposure parameters I decided to analyse it myself. I feel like the results might be of interest of even helpful to some of you. So here we go:
Camera: Pentax K-5
Light-Metering: 77 Segment TTL
Autofocus: Center Spot
Auto ISO settings: 80-1600 // SLOW (camera raises ISO very conservatively)
White Balance: auto
SR: 1
lens: da* 16-50 2.8 @ 16mm and 50mm
*****
Mode M: Exposre correction only changes the zero point of the light meter but NOT the actual exposure parameters(ISO, aperture, shuttertime). This is of practical relevance for the use of green auto exposure button.
Mode Av: Camera changes only the shuttertiming. If the desired correction exceeds the camera's possibilities it just tries to do the maximum possible.
Mode Av + Auto ISO: Camera tries to keep shutter time faster than 1/25s (1/50s@ 50mm), so it first changes the ISO and only goes for longer shutter times if the ISO is already at maximum.
Mode Tv: Camera changes only the Aperture. If the desired correction exceeds the camera's possibilities it just tries to do the maximum possible.
Mode Tv + Auto ISO: The Camera tries to avoid stopping down more than 10, so it first tries to adjust the ISO.
Mode Sv: Highlight -> The camera tries to avoid stopping down more than 10 ; Lowlight -> Camera tries to keep shutter time faster than 1/25s (1/50s@ 50mm)
Mode TAv: Camera only changes ISO. If the desired correction exceeds the camera's possibilities it just tries to do the maximum possible.
Mode P: Camera reacts analogue to mode Av respectively mode Tv
Now does the SR-unit influence these algorhitms?
Yes, with the SR-unit disabled the focal length specific shutter time tresholds mentioned above seem to be non existent.
*****
Of course this is not the full story. At the moment this only shows how the camera reacts under those specific conditions. There are many open questions. I wonder specifically:
Can the results be modulated by changing the Auto ISO sensitivity setting (SLOW/NORMAL/FAST)?
What shutter time treshhold is chosen when using a manual lens? Maybe it is dependent on the focal length you set up in the camera?
What happens when using flash(es)?
Which other parameters affect exposure correction? For example the camera might prefer shorter exposure times when in AF-C mode to avoid motion blur.
I am looking forward to your input. Sorry for my clumsy verbalization.
Best,
Florian
http://www.flickr.com/photos/floriko/
http://floriko.wordpress.com/ |
